Production, quality control, and biodistribution studies of 141Ce-EDTMP as a potential bone pain palliation agent

The purpose of the present work was to introduce 141Ce-EDTMP as a novel potential future pain palliative agent to patients suffering from disseminated skeletal metastases and diagnostic imaging radioisotope as well. Cerium-141 [T1/2 = 32.501 days, Eβ (max) = 0.580 (29.8%) and 0.435(70.2%) MeV, Eγ = 145.44 (48.2%) keV] possesses radionuclidic properties suitable for use in palliative therapy of bone metastases. 141Ce also has gamma energy of 145.44 keV, which resembles that of 99mTc. Therefore, the energy window is adjustable on the Tc-99m energy because of imaging studies. 141Ce can be produced through a relatively easy route that involves thermal neutron bombardment on natural CeO2 in medium flux research reactors (4–5×1013 neutrons/cm2·s). The requirement for an enriched target does not arise. Ethylenediamine (tetramethylene phosphonic acid) (EDTMP) was synthesized and radiolabeled with 141Ce. The experimental parameters were optimized to achieve maximum yields (>99%). The radiochemical purity of 141Ce-EDTMP was evaluated by radio-thin layer chromatography. The stability of the prepared formulation was monitored for one week at room temperature, and results showed that the preparation was stable during this period (>99%). Biodistribution studies of the complexes carried out in wild-type rats exhibited significant bone uptake with rapid clearance from blood. The images showed high uptake of complex in bone after 72h and 2 weeks clearly. The percentage injected dose per gram of tissue (%ID/g) for each organ or tissue was calculated. The results show significant bone uptake with rapid clearance from blood. The properties of produced 141Ce-EDTMP suggest applying a new efficient bone pain palliative therapeutic agent to overcome metastatic bone pains.